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DMN Elements

A DMN model is visualized as a Decision Requirements Diagram (DRD). This diagram shows the dependencies between various elements, describing how a decision is reached.

The DRD Graph​

In a DRD, information flows downwards. Input data feeds into decisions, and decisions can feed into other decisions. This creates a directed graph of dependencies.

Core Elements​

The following are the standard graphical elements you will use to build your decision models:

Decision​

The core building block. Represented by a rectangle. A decision takes inputs (from Input Data or other Decisions) and uses an expression to calculate an output value.

Input Data​

External information. Represented by an oval. Input Data denotes information that comes from outside the decision model (e.g., from an API call, a database, or user input).

Business Knowledge Model (BKM)​

Reusable logic. Represented by a rectangle with clipped corners. BKMs allow you to define a function once and reuse it across multiple decisions.

Decision Service​

Encapsulated sub-model. Represented by a rounded rectangle with a horizontal line. A Decision Service defines a reusable interface that invokes a subgraph of decisions.

Knowledge Source​

Metadata & Authority. Represented by a wavy shape. It links dependencies to external sources of authority, such as policies, regulations, or documents, explaining why a decision exists.

Connectivity​

Elements are connected by lines representing requirements:

  • Information Requirement: A solid line indicating data flow (e.g., Input Data -> Decision).
  • Knowledge Requirement: A dashed line indicating logic invocation (e.g., BKM -> Decision).
  • Authority Requirement: A dashed line indicating a dependency on a knowledge source.